1. Field of the Invention
The invention relates generally to the field of gas turbine plants, and more specifically to gas turbine plants which use solar energy to heat the gas flowing through the turbine before it is coupled to the turbine.
2. Description of the Prior Art
In recent years, solar energy has been applied to a wide range of uses, including domestic heating and hot water, using flat plate collectors, solar stills, and solar cookers, and so forth. In addition to the flat-plate collectors, solar receivers having various geometric shapes have been used to concentrate the received sunlight and thereby increase the temperatures from slightly over 100.degree. Fahrenheit for flat-plate collectors into the thousands of degrees. For example, parabolic troughs and conical concentrators, which can receive sunlight and focus it onto a line or target, can generate temperatures in the 2000.degree. to 3000.degree. range, and paraboloids, which can concentrate the sunlight to a point target, have been known to generate temperatures in the 5000.degree. to 6000.degree. range.
Advances in solar energy technology have allowed solar receivers and collectors to be used in a number of industrial applications, such as in heat and steam engines and for generating electricity. However, because of variations in weather and air pollution, solar receivers may be shielded from the sun to varying extents for long periods of time, which can result in lowering power outputs as the amount of sunlight received by the receiver is reduced. Indeed, in some instances the amount of sunlight reaching the receiver may be so reduced that operation of the equipment may be impractical or impossible. Indeed, it normally is impossible to run these devices at night. Accordingly, the usefulness of solar receivers has been limited.
In some cases it would be possible to provide an auxiliary power source in addition to the solar receiver to boost the power output when sufficient sunlight is not available. However, this can be quite expensive. Furthermore, for the majority of the time that enough sunlight is available, it can supply the vast majority of the energy required, and the incremental amount required from an auxiliary energy supply may be so low as to keep the auxiliary supply from operating efficiently if at all. For example, in gas turbine operation it may be desirable to provide an auxiliary energy supply, typically using fossil fuels, should sunlight be insufficient to power the turbine. However, the amount of energy required would often be so small that not enough fuel would be needed to allow a high enough concentration for combustion.